Explanation: caution: vigilance; Preparation: prevention. The security is extremely tight.

From: Mandarin Jinsan: "Learn from the lessons of Japanese exams and be vigilant."

Example: I remember it was a scorching sun, and there were more than 20,000 people sitting on the big playground outside.

◎ Chen Ruoxi's Ren Lanxiu

Grammar: subject-predicate type; As predicate, object and attribute; Describe a tight defense